The Boston subway system will soon host simulated biological weapon attacks as the Department of Homeland Security's Science and Technology Directorate (S&T) conducts tests of sensors designed to detect the presence of biological agents in metropolitan areas.

After temporarily shutting down the transportation system, S&T will release small quantities of harmless and inactive bacteria into subway tunnels under Beantown and monitor the spread of the dead microbes using newly developed sensors. The bacterium, Bacillus subtilis, is considered nontoxic even when alive and active.

S&T will be conducting the tests—which are part of its Detect-to-Protect (D2P) project—for the next 6 months, according to the Department of Homeland Security. Anne Hultgren, director of the D2P project, said that the tests will help determine if the new sensors, designed by a suite of contractors, are up to snuff. "While there is no known threat of a biological attack on subway systems in the United States, the S&T testing will help determine whether the new sensors can quickly detect biological agents in order to trigger a public safety response as quickly as possible," she said in a statement.

The new tests come at a precarious time for US anti-bioterrorism efforts. Last week, the Los Angeles Times reported that BioWatch, the federal government's key biological attack detection system, is prone to false alarms—many of which have occurred since its inception in 2003.

It's rather interesting, actually. There's always risk, but still. This doesn't seem too different from treated tap water. I'm not going to freak out about this stuff too much; the crap we carelessly put in the air via combustion engines is far more deadly and worrisome.